The present invention relates to a socket for an electrical part for detachably holding an electrical part such as semiconductor device (called iIC packagei hereinlater).
A socket for an electrical part of the kind mentioned above having a conventional structure is shown in FIGS. 9 and 10, in which an IC package 1 as the electrical part is detachably held by an IC socket 2.
The IC package 1 is so-called a gull-wing type one having a rectangular or square package body 1a and a plurality of IC leads 1b as terminals projecting sideway from the package body 1a.
The IC socket 2 is composed of a socket body 3, a mount portion 3a on which the IC package 1 is rested and a guide portions 3b, disposed so as to correspond to respective corner portions of the rectangular IC package 1 when rested, for positioning the rectangular IC package 1 to a predetermined position.
Further, a plurality of contact pins 4, which are elastically deformable and contacted to or separated from the IC leads 1b of the IC package 1, are arranged to the socket body 3. Each of the contact pins 4 is composed of a stationary contact piece 4a and a movable contact piece, not shown, disposed on the upper portion of the stationary contact piece 4a, and the IC lead 1b of the IC package 1 is interposed and clamped between the stationary contact piece 4a and the movable contact piece.
Furthermore, there is also provided an upper operation member, not shown, for the socket body 3 to be vertically movable. When the upper operation member is lowered against the urging force of a spring, the movable contact piece of the contact pin 4 is elastically deformed and hence separated from the IC lead 1b and, on the other hand, when the upper operation member is raised upward, the movable contact piece returns by the elasticity and depresses the IC lead 1b from the upper side thereof to clamp it between the movable and stationary contact pieces.
The stationary contact pieces 4a are projected upward by a predetermined amount from the mount portion 3a so as to prevent dust or dirt from adhering to the stationary contact pieces 4a and staying between them and the IC leads 1b.
In the conventional structure mentioned above, a countermeasure against the adhering or staying of the dust or dirt by locating the stationary contact pieces 4a so as to project, by a predetermined distance, upward from the upper surface of the mount portion 3a. However, when the IC package 1 is mounted to the predetermined position, there may cause a case where the IC package 1 is somewhat inclined at the initial stage of mounting. In such a case, there is a fear such that, as shown in FIG. 9, the stationary contact pieces 4a and the IC leads 1b are shifted in their positions and the IC leads 1b are dropped down from the stationary contact pieces 4a, and under such state, when the position or attitude of the IC package 1 is corrected with its horizontal state maintained, the IC leads 1b may be deformed, resulting in a defective contacting condition to the stationary contact pieces 4a.